Hydrogen-terminated diamond field-effect transistor with AlO_x dielectric layer formed by autoxidation

Fabrication of hydrogen-terminated diamond (H-diamond) field-effect transistor (FET) with AlO_x dielectric layer has been successfully carried out. The AlO_x layer was formed by auto-oxidizing 6 nm Al film in the air at room temperature, and a FET without AlO_x dielectric layer has also been fabricated for comparison. For both FETs, 100 nm Al layers were deposited as the gate electrodes, respectively. The leakage current density in FET with AlO_x dielectric layer was four magnitude orders lower than that without AlO_x dielectric layer at V_GS = -5 V, indicating that AlO_x dielectric layer could effectively reduce leakage current and prevent reverse I_D in I_D - V_DS caused by defects on diamond surface. Distinct pinch-off characteristic with p-type channel was observed in I_D - V_DS measurement. The threshold voltage was -0.4 V at V_DS = -15 V.